It's probably true that trading in any sort of unregistered or un-tracked financial instrument is or will soon be illegal in most jurisdictions.  That's why any type of decentralized exchange, to be successful in the long run, must be anonymous/pseudonymous.  On the positive side, all of the restrictions governments are imposing on fiat currencies are making them less and less like real money every day.  That can only bode well for the value of cryptocurrencies, and we may soon be much less interested in exchanging them with fiat.